Experiments using congenic resistant lines of inbred mice and RhL-A matched rhesus monkeys indicated that under defined genetic conditions teeth can be transplanted in weakly disparate hosts without inducing a destructive immune response. The purpose of the proposed research is to define the genetic criteria required for long-term survival of transplanted teeth in non-human primates and to describe the immunological events elicited by tooth allografts in mice and rhesus monkeys. In mice, tooth allografts will survive indefinitely when as many as 2 non-H-2 antigen differences exist between donor and recipient. Experiments are described which would determine if immunoblocking antibodies contribute to their unexpected survival. Active enhancement will be studied by determining the survival times of second-set donor-strain skin grafts on recipients of primary tooth allografts. In addition, mouse anti-tooth serum will be studied for its ability to prolong the survival of primary skin allografts. Other experiments will determine the effect of the components of the major histocompatibility complex on tooth allograft survival. RhL-A matched rhesus monkeys which have received tooth transplants will be tested for responsiveness in mixed lymphocyte culture. Monkey anti-tooth sera will be assayed for lymphocytotoxicity at critical periods following orthotopic tooth transplantation and for its ability to either enhance or curtail the mixed lymphocyte reaction. The clinical and radiographic status of tooth transplants in monkeys will be followed for at least 2 years to characterize the effect of genetic matching on graft stability in vivo. Second-set donor and unrelated third-party skin grafts will be done to assess the degree to which teeth systemically sensitize the host to donor-specific histocompatibility antigens. The transplants will then be removed and examined histologically. It is hoped that enough definitive information will be obtained to confidently predict the success of tooth transplants among humans. A viable functioning tooth graft would have many physiologic and mechanical advantages over conventional methods of restoring deficient dentitions.